Lung function predicts mortality: 10-year follow-up after lung cancer screening among asbestos-exposed workers

Purpose

To assess the predictive value of lung function impairment on mortality among asbestos-exposed workers.

Methods

A total of 590 workers originally screened for occupational lung disease including spirometry and pulmonary diffusing capacity measurements were followed up for mortality data (ICD-10 classification). The mean follow-up time was 10.5 years. Associations of different lung function parameters with mortality from all causes and from cardiovascular (I00-I99) and non-malignant respiratory diseases (J00-J99) were analysed. Factor analysis was used to create obstructive and restrictive factors.

Results

A total of 191 deaths were found altogether. Most measured lung function variables were associated with increased mortality when studied separately. Both decreased forced expiratory flow in one second (hazard ratio/measurement unit = 0.977, 95 % CI 0.969–0.988, p < 0.001) and impaired diffusing capacity (0.973, 0.965–0.981, p < 0.001) were independently associated with mortality from all causes, as well as from cardiovascular and non-malignant respiratory diseases. Both obstructive factor alone and the sum of obstructive and restrictive factors were associated with all studied mortality categories. The restrictive factor alone was associated with all-cause and respiratory mortality.

Conclusions

Deteriorated lung function predicts deaths. The reasons for impaired lung function should be medically explored to enable restoring measures aiming thus to prevent premature deaths.     

Aluminium dust-induced lung disease in the pyro-powder-producing industry: detection by high-resolution computed tomography

Objective: The aim of this case study was to investigate the suitability of high-resolution computed tomography (HRCT) for detecting early stages of lung fibrosis induced by aluminium (Al) dust. Methods: A 40-year-old worker was studied who had worked as a stamper for 14 years in a plant producing aluminium powder and had been exposed to high levels of aluminium dust during this time. The investigation included the collection of general data on health and details on occupational history, immunological tests, a physical examination, lung function analysis, biological monitoring of Al in plasma and urine, chest X-rays and HRCT. Results: For many years the man has suffered from an exercise-induced shortness of breath. Lung function analysis revealed a reduction of the vital capacity to 57.5% of the predicted value. The Al concentration in plasma was 41.0 μg/l (upper reference value 10 μg/l) and in urine 407.4 μg/l [upper reference value 15 μg/l, biological tolerance (BAT) value 200 μg/l] at the time of diagnosis. Chest X-ray showed unspecific changes. HRCT findings were characterised by small, centrilobular, nodular opacities and slightly thickened interlobular septae. Exposure to other fibrotic agents could be excluded. Conclusions: HRCT was more sensitive than chest X-rays for detecting this early stage of Al-dust-induced lung disease. The suitability of HRCT in the surveillance of workers highly exposed to aluminium powder should be evaluated in further studies. Biological monitoring can be used to define workers at high risk. Received: 29 March 1999 / Accepted: 26 August 1999     

Reactions of asbestos-exposed workers to notification and screening

In the wake of efforts to pass legislation mandating notification of workers at high risk of developing occupational disease, considerable controversy exists regarding the potential costs and benefits of such notification efforts. It has been suggested that individual notification would cause undue psychological distress, especially when primary prevention efforts are no longer possible. In this study, we assessed reactions of asbestos-exposed workers to a letter notifying them of their risk for asbestos-related illnesses and the availability of a medical screening program. Two hundred forty-seven workers who attended the screening program and 53 who chose not to attend completed a questionnaire that tapped reactions to notification. Workers reported neither undue psychological distress nor avoidance behavior in response to notification, and many respondents reported engaging in active and appropriate coping behaviors. Workers who first learned of their risk through the notification letter (33.7%) were no more likely to report distress or denial than were workers who had learned previously through other sources. Individuals who chose not to attend the screening program were less likely than attenders to report experiencing distress upon learning of their risk status, more likely to engage in minimization of risk, and less likely to have taken direct action. Our results suggest that the psychological costs of notifying workers of increased risk for asbestos-related illness appear to be outweighed by the benefits of notification and screening.     

Lung function in asbestos-exposed workers, a systematic review and meta-analysis

Background

A continuing controversy exists about whether, asbestos exposure is associated with significant lung function impairments when major radiological abnormalities are lacking. We conducted a systematic review and meta-analysis in order to assess whether asbestos exposure is related to impairment of lung function parameters independently of the radiological findings.

Methods

MEDLINE was searched from its inception up to April 2010. We included studies that assessed lung function parameters in asbestos exposed workers and stratified subjects according to radiological findings. Estimates of VC, FEV₁ and FEV1/VC with their dispersion measures were extracted and pooled.

Results

Our meta-analysis with data from 9,921 workers exposed to asbestos demonstrates a statistically significant reduction in VC, FEV₁ and FEV₁/VC, even in those workers without radiological changes. Less severe lung function impairments are detected if the diagnoses are based on (high resolution) computed tomography rather than the less sensitive X-ray images. The degree of lung function impairment was partly related to the proportion of smokers included in the studies.

Conclusions

Asbestos exposure is related to restrictive and obstructive lung function impairment. Even in the absence of radiological evidence of parenchymal or pleural diseases there is a trend for functional impairment.     

Pulmonary function,smoking habits,and high resolution computed tomography (HRCT) early abnormalities of lung and pleural fibrosis in shipyard workers exposed to asbestos

To evaluate the presence of asbestos-related pleural and parenchymal abnormalities and their correlation with pulmonary function and smoking habits, 119 asbestos-exposed asymptomatic workers (mean age, 46.2 years; mean duration of asbestos exposure, 8.6 years; mean latency time, 21.6 years) with normal standard P-A chest radiographs were submitted to HRCT, CO-diffusing capacity, and pulmonary function tests. HRCT scans were normal only in 31 (26%) examined workers; 31 (26%) subjects showed both pleural and parenchymal involvement, and 50 (42%) and seven (6%) had exclusively pleural and parenchymal abnormalities, respectively. Based on CO-diffusing capacity and pulmonary function tests, no significant difference was demonstrated between workers with pleural lesions and subjects with normal pleura; however, lower values of FVC were observed in the nonsmoking workers with parenchymal abnormalities in comparison with nonsmoking subjects with normal parenchyma (78.2 vs. 89.7% of predicted values; p = 0.03 by student's two-tailedttest), and lower values of FEV₁/FVC in the smokers with parenchymal lesions with respect to smokers with normal parenchyma (93.7 vs. 100.2% of predicted values; p = 0.005 by student's two-tailedttest). In conclusion, our results demonstrate that HRCT may detect early parenchymal abnormalities which correlate with exposure to asbestos and respiratory function impairment, including a reduction in obstructive indices in smokers occupationally exposed to asbestos, without any clinically evident disease. © 1996 Wiley-Liss, Inc.     

Clinical and HRCT screening of heavily asbestos-exposed workers

Purpose  

To characterize asbestosis today and to clarify the indications for high-resolution computed tomography (HRCT) in the surveillance of heavily exposed workers.     

Chest radiography and high resolution computed tomography in the evaluation of workers exposed to silica dust: relation with functional findings.

OBJECTIVES--To compare the usefulness of high resolution computed tomography (HRCT) with chest radiography (CR) in the diagnosis and assessment of severity of silicosis. METHODS--27 workers exposed to silica underwent CR, HRCT, and pulmonary function tests. Two experienced readers independently evaluated CR by International Labour Office classification, and grouped the results into four categories. HRCT categories of nodule profusion and the extent of emphysema were graded on a four point scale; in 20 subjects the percentage distribution of lung densities were measured by HRCT. RESULTS--Concordance between readers was higher for HRCT than for CR (K statistic = 0.49 and 0.29 respectively). There was poor concordance between CR and HRCT in the early stage of silicosis. No significant difference in pulmonary function tests was found among different CR categories, but forced expiratory volume in one second (FEV1), maximal expiratory flow at 50% and 75% of FVC (MEF50, MEF75), and diffusion capacity significantly decreased with increasing HRCT categories. Subjects with simple silicosis detected by HRCT had a lower FEV1 than subjects without silicosis, whereas subjects with conglomerated silicosis showed higher residual volume and functional residual capacity than subjects with simple silicosis. These relations were not affected by smoking or symptoms of chronic bronchitis. Different grades of emphysema detected by HRCT were significantly different in diffusion capacity. Only the HRCTs of the lowest and the highest categories of profusion of parenchymal opacities were significantly different in their distribution of density classes. CONCLUSION--HRCT is more reproducible and accurate than CR, as suggested by the higher agreement between readers and the better correlation with pulmonary function tests, irrespective of smoking and chronic bronchitis; however, these data do not support the hypothesis that HRCT is more sensitive than CR in the early detection of silicosis.     

High prevalence of reversible airway obstruction in asbestos-exposed workers

In this retrospective study of 97 male workers exposed to asbestos for 2-50 yr, data were collected on chest x-ray findings and lung function, including lung volumes, forced expiratory flow rates (i.e., forced expiratory volume in 1 sec [FEV1.0], forced expiratory flow measured between 25% and 75% of forced vital capacity [FEF(25-75%)]), airway resistance (R(aw)), carbon monoxide (CO)-diffusing capacity, and the existence of airway obstruction reversible by a beta-adrenergic agonist (RAO). The authors performed multiple-regression analyses to correlate the variations in lung function data with age, smoking habits, duration of asbestos exposure, and time since last exposure. Occupational activities of subjects that might induce specific lung abnormalities were also considered. No significant decrease was seen in lung volumes or CO-diffusing capacity; however, a decrease in FEV1.0 and an increase in R(aw) were measured in 65% of the subjects, and an isolated decrease in FEF(25-75%) occurred in only 18%. There was no difference in lung-function data between subjects who had chest x-ray signs of abnormalities (n = 59) and those who did not (n = 38). A significant relationship was found between the decrease in FEV1.0 and age; however, no correlation was noted between altered lung function and cigarette smoking, duration of asbestos exposure, or time since last exposure. RAO prevalence was higher (34%) than previously reported (9%) in subjects with chronic obstructive pulmonary disease (COPD) who were not exposed to asbestos or outdoor pollution. The RAO prevalence in asbestos-exposed workers was nearly the same as that measured in COPD subjects who lived downtown and who were exposed to outdoor pollution (36%). The high RAO prevalence in asbestos-exposed workers was found in 43% of subjects who were exposed only to asbestos, and in 33% of subjects who were also exposed to air pollution due to their occupational activities. It is hoped that the observations in this study will encourage practitioners to check for RAO in asbestos workers who use inhaled bronchodilators.     

Cytological analysis of bronchoalveolar lavage fluid in asbestos-exposed workers

Background:Asbestos-related lung diseases are a group of heterogeneous disorders with different pathogenesis and prognosis. Very few studies investigated the BALF cell profile of asbestos exposed workers. The existence of a relationship between bronchoalveolar lavage fluid (BALF) cellular pattern and specific diagnosis and/or asbestos exposure biomarkers would allow the identification of effect biomarkers useful in the follow up of asbestos-exposed workers and in the diagnosis of asbestos-related diseases.Objectives:To assess BALF cell profile in formerly asbestos-exposed workers and its relationship with asbestos fibre (amphibole and chrysotile) and asbestos body (AB) concentrations.Methods:113 male workers formerly exposed to asbestos underwent bronchoscopy with bronchoalveolar lavage and were retrospectively enrolled. 35 of them were affected by pleural plaques and 10 were affected by asbestosis. Pulmonary functional tests (PFT), BALF cellular pattern, BALF mineralogical analysis with asbestos fibres and AB counting were performed in each patient. A statistical analysis with a multivariate linear regression model was adopted.Results:From the statistical analysis of data a direct correlation between pack-years and BALF macrophages was found. Inversely correlation between pack-years and BALF lymphocytes was detected. There was not relationship among BALF cellular pattern, PFT values, specific diagnosis, BALF AB count or BALF asbestos fibre concentration.Discussion:BALF cellular pattern does not seem to be related to asbestos exposure biomarkers like AB and asbestos fibre concentration in BALF. Instead, smoke habit can induce an increase in BALF macrophages and a decrease of BALF lymphocytes count.Key words: Bronchoalveolar lavage, asbestos, asbestosis, neutrophils, lymphocytes, macrophages     

Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests.

The lungs of 50 symptom free workers exposed to amosite and with normal pulmonary function tests were examined by high resolution computed tomography (HRCT). Twenty five had normal standard chest radiographs whereas the other 25 had radiographs interpreted as near normal (International Labour Office profusion score < 0/1 or suspected pleural plaques). In 13 of the workers the results of HRCT were negative; in 22 pleural plaques were found, in five there was only parenchymal involvement, and 10 had both pleural and parenchymal changes. The mean duration of exposure to amosite was significantly longer for the subjects with parenchymal signs than for those with normal parenchyma and for the workers with pleural plaques than for those with normal pleura and lung parenchyma. The prevalence of identified pleural and parenchymal abnormalities in the 50 workers was also significantly higher than in a reference group without exposure to asbestos. It is concluded that HRCT may detect initial lung and pleural involvement in symptom free workers exposed to amosite and the mean duration of exposure is longer for subjects with parenchymal or pleural involvement.     

Role of computed tomography in evaluating asbestos related lung disease

To find how computed tomography (CT) may be effectively used in individuals with suspected asbestos related lung disease 30 men with a history of exposure to asbestos were studied. All subjects underwent high kilovoltage posteroanterior and left lateral chest radiographs and chest CT. Eighteen were randomly selected asbestos workers referred for routine surveillance. The remaining 12 were patients who had been referred for investigation of respiratory symptoms or abnormal routine chest radiograph, or both, and found to have chest radiographic changes compatible with asbestos related lung disease. In the group referred for routine surveillance both pleural shadowing and pulmonary shadowing were shown on CT but not chest radiographs in only one case. Five were thought to have pleural shadowing on chest radiographs but this was confirmed on CT in only one case. All 12 patients referred for investigation showed pleural shadowing on chest radiographs; this was confirmed in all cases on CT which also showed unsuspected pulmonary shadowing in five cases. These findings suggest that it is not appropriate to use chest CT routinely in all asbestos workers referred for routine surveillance. When CT is used selectively in those with pleural shadowing on plain chest radiography, however, it is helpful in refuting or confirming the presence of pleural disease and may show unsuspected pulmonary shadowing.     

Medical monitoring of asbestos-exposed workers: experience from Poland

In Poland, the use of asbestos was banned in 1997 and asbestos plants have been closed since then. Despite their closure, cases of asbestos-related occupational diseases among former asbestos workers are still being recorded in the Central Register of Occupational Diseases. Between 2001 and 2014, there were 2726 asbestos-related illnesses, classified and reported as diseases associated with occupational exposure to asbestos. In 2000, Poland introduced a programme called Amiantus, targeted at former asbestos-processing plant workers. The programme provided periodic medical examinations to workers and free access to medications for treatment of asbestos-related illnesses. Introduction of the programme provided additional data to generate a reliable estimation of the number of asbestos-related occupational diseases, including cancer. The average latency period for asbestosis, lung cancer and mesothelioma is about 40 years so there may still be some health impact to former workers necessitating follow-up. We present the Polish experience of implementing a medical examination programme for asbestos-exposed workers and provide a list of activities to consider when planning for such a programme.     

肺功能及高分辨CT在间质性肺疾病中的相关性研究

目的 对间质性肺疾病患者影像学、肺功能及临床表现进行相关分析,评价肺功能特别是脉冲振荡(IOS)测定呼吸阻抗在该疾病诊断中的意义.方法 对56例间质性肺疾病患者的呼吸阻抗、常规肺功能、静息时动脉血氧分压(PaO2)及肺部高分辨CT评分和呼吸困难评分进行分析.结果 振荡频率在5 Hz时的电抗(X5)、在20 Hz时的电抗(X20)与肺活量(VC)呈正相关(r=0.699、0.537,P＜0.05),与用力肺活量(FVC)呈正相关(r=0.690、0.473,P＜0.05),与一氧化碳弥散量(DLCO)呈正相关(r-=0.494、0.301,P＜0.05),与PaO2呈负相关(r=-0.621、-0.411,P＜0.05);响应频率与VC、FVC、DLCO呈负相关(r=-0.658、-0.639、-0.352,P＜0.05),与PaO2呈正相关(r=0.277,P＜0.05);特发性肺间质纤维化患者的病程较结缔组织病所致间质性肺疾病患者的病程明显延长(P＜0.05),其余观察指标差异无统计学意义(P＞0.05).结论 常规肺功能指标VC、FVC、DLCO及呼吸阻抗指标响应频率、X5对肺间质纤维化的诊断有一定的意义;IOS测定呼吸阻抗对间质性肺疾病患者肺功能损害的动态监测和疗效评价具有一定的应用前景;应重视结缔组织病患者的影像学和肺功能检查以便及时发现肺部早期病变.